extemporaneous

adj

1. With inadequate preparation or without advance thought; offhand.

   “My speeches in Great Britain were wholly extemporaneous, and I may not always have been so guarded in my expressions, as I otherwise should have been. I was ten years younger then than now, and only seven years from slavery.”

   ““Who the devil is there in Ramilly County,” muttered Amory aloud, “who would deliver Verlaine in an extemporaneous tune to a soaking haystack?””

   “The lovely words of a prepared speech, however, cannot erase extemporaneous words and deeds, thousands of them, that have run contrary to those aspirations.”